Species specific compounds from plants are important to many areas of science and medicine. The ability to achieve yields of species specific compounds approaching those found in the plant in a wide range of plant cell cultures would open new possibilities for providing valuable compounds currently isolated from plants. Valuable compounds whose supply is limited by the availability of plants might be prime candidates for such a technology. Examples of such compounds would be some of the antineoplastic compounds isolated from plants, e.g., bruceantin, maytansine, and taxol. Plant cell cultures usually produce very small amounts of species specific compounds when compared to the plant. However, there are now approximately 20 cases where plant cell cultures produce amounts of species specific compounds approaching and in some cases exceeding those found in the plant. From these cases and other evidence, it is possible to conclude that the yield of desired compound in plant cell cultures can be changed by: 1) The genotype of the plant from which the cultures were initiated. 2) Differences in cells in the primary explant. 3) Selection of low yielding cell lines by culture conditions. 4) Cells becoming low yielding in culture by random destruction of genetic information or by stable alteration of phenotype. 5) Culture conditions not appropriate for synthesis of the desired compound. We propose to evaluate these possibilities using the production of nicotine by cell cultures of N. tabacum as a model system. This system was chosen because all the technical requirements for the study have been previously established.